Alpha synuclein dimers and oligomers are increased in overexpressing conditions in vitro and in vivo.

Parkinson's disease is characterized by degeneration of dopaminergic neurons in the substantia nigra pars compacta along with the formation of intracellular fibrillar inclusions (Lewy bodies and Lewy neuritis), which are mainly composed of aggregated α-synuclein (ASYN). This latter is a 14 kDa protein that localizes to synaptic vesicles in nerve terminals and promotes soluble N-ethylmaleimide-sensitive factor attachment protein receptor complex assembly. We explored the monomeric and oligomeric state of ASYN in vitro in HEK293s and SH-SY5Y cell lines. In addition rats were injected in the substantia nigra with an Adeno associated virus carrying the human A53T mutation of ASYN (in vivo experiments). We show that human wild type ASYN as well as PD-linked mutations (A30P, E46K and A53T) in overexpressing conditions mostly exists in a monomeric state in equilibrium with dimeric forms. The monomer/dimer ratio is unaffected by PD-linked mutation. Furthermore, the A30P, E46K and A53T mutations overexpression strongly increased cell death compared to wild type ASYN. Taken together, our data suggest that ASYN dimers amount do not directly correlate to reduced cellular viability, suggesting a different role in protein function and induced pathology. Our data suggest that early ASYN neuro-pathogenic effects are probably mediated by other molecular processes than increased oligomerization alone.

Pregabalin antagonizes copper-induced toxicity in the brain: in vitro and in vivo studies.

BACKGROUND: Copper plays key roles in brain metabolism. Disorders of copper metabolism impact on neural signaling. The intracellular and extracellular concentrations of copper are tightly regulated. Pregabalin is a drug with multiple modes of action and has a high-affinity binding site for the alpha2delta subunit of voltage-gated calcium channels. METHODS: Assessment of neuroprotective effects of pregabalin using cell culture, transcription studies, microdialysis and neurophysiological assessment in rats. RESULTS: In vitro, copper decreased markedly the survival of neuronal cells and enhanced the production of nitric oxide (NO). Transcription of NO synthase (NOS) 1-3 and PGC-1a (a key regulator of mitochondrial biogenesis) was activated. In vivo, copper impaired the NMDA-mediated regulation of glutamate in the brain, increased the production of NO and enhanced markedly the excitability of the motor cortex. Pregabalin had antagonistic effects both in vitro and in vivo. CONCLUSION: Our experiments highlight that pregabalin antagonizes the neurotoxic effects of copper. We argue that pregabalin exerts neuroprotective effects by silencing the overexcitability state induced by copper. We propose a possible use of pregabalin for treatment of disruption of copper homeostasis.

Past, present and future therapeutics for cerebellar ataxias.

Cerebellar ataxias are a group of disabling neurological disorders. Patients exhibit a cerebellar syndrome and can also present with extra-cerebellar deficits, namely pigmentary retinopathy, extrapyramidal movement disorders, pyramidal signs, cortical symptoms (seizures, cognitive impairment/behavioural symptoms), and peripheral neuropathy. Recently, deficits in cognitive operations have been unraveled. Cerebellar ataxias are heterogeneous both at the phenotypic and genotypic point of view. Therapeutical trials performed during these last 4 decades have failed in most cases, in particular because drugs were not targeting a deleterious pathway, but were given to counteract putative defects in neurotransmission. The identification of the causative mutations of many hereditary ataxias, the development of relevant animal models and the recent identifications of the molecular mechanisms underlying ataxias are impacting on the development of new drugs. We provide an overview of the pharmacological treatments currently used in the clinical practice and we discuss the drugs under development.